There is the only {#LLD_MACROS} available for defining as context of user macroses into trigger expressions now. It allows to use flexible trigger expressions for different item prototypes in LLD.

But, out of LLD, for regular items or, if we want to create trigger flexibility based on diffferent hosts - we are not able to do that and have to create different trigger expression with different threshold value on the host level as well

Because context  is a static value -it would be great to use hostname-based macroses ({HOST.HOST},{HOST.NAME}) or  some regex pattern as a context into trigger expression to automatize flexibility when we have to use different thresholds for different hosts